The purpose of this research is to use the Samputensili rotating instrument. During the research, some inspection values have been used are as follows; Fi-rotating deviation, Fr-rotational concentricity error, and fl-tooth to tooth error. This paper is focused on the relation between the change of diameter pressure and inspection values. After analyzing, it turns out that the largest loading torsion of a rotation instrument will best to work under a module 2's gear. And its greatest loading pressure will be best under 550g's diameter pressure. Under the circumstances, the inspection result will be remained most stable. After a further adjusting the diameter pressures to do the short time inspection in order to determine the grade and quality of a gear, which may upgrade the rotating instrument.